Methods and apparatus for low power wireless communication

ABSTRACT

Embodiments include methods and apparatus for wireless network communication between a device that operates a radio in compliance with a wireless communication standard and another device that may not be capable of complying with the wireless communication standard. In an embodiment the non-complaint device is a receiver only. Information is broadcast or advertised or otherwise transmitted by the compliant device according to the protocol and embodiments encode information on top of the protocol for decoding by the receiving device, which does not decode the protocol.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation-in-part (CIP) of U.S. patentapplication Ser. No. 14/213,771, filed Mar. 14, 2014 U.S. patentapplication Ser. No. 14/213,771 claims priority to and the benefit ofU.S. Provisional Application No. 61/782,220, filed Mar. 14, 2013. Eachof the foregoing patent applications is incorporated by reference hereinin their entirety.

BACKGROUND

Known wireless communication devices such as a typical mobile telephoneor a tablet personal computer (PC) each typically includes one ofseveral types of commercial transceiver or radios, such as multi-bandcellular, Wi-Fi®, Bluetooth®, and Global Positioning System (GPS). Eachof these transceivers includes an integrated circuit (IC), or collectionof ICs designed for a specific wireless communication standard (e.g.,the Bluetooth® standard). Furthermore, the wireless standards aredefined by a group such as the Institute of Electrical and ElectronicsEngineers (IEEE) (e.g., Wi-Fi®), or by a consortium (e.g., Bluetooth®).Such wireless standards typically have mandatory modes that must besupported by an IC to be considered “compliant” with that standard.Compliance with the standard is used to provide interoperability amongdevices from different manufactures. Because of the complexity of thesestandards, and the “overhead” circuits used to support at least themandatory functionality of the standard, transceiver ICs that arestandard-compliant typically consume higher power than customtransceivers that do not target any specific standard. For example, aBluetooth®-compliant transceiver from Texas Instruments (T1) typicallyconsumes >40 mW in the active mode, while a proprietary transceiver fromEnergy Micro consumes <10 mW.

Any wireless peripheral device such as, for example, a headset or astereo, that wirelessly connects to a wireless communication devicetypically does so using one of the wireless connectivity standards thewireless communication device supports (e.g. iPhone®, Wi-Fi® andBluetooth®; Galaxy SIII®; Wi-Fi®, Bluetooth®, and Near FieldCommunication). This means the wireless peripheral device typically alsouses a standard-compliant IC to provide interoperability between thewireless communication device and the wireless peripheral device. Whilethe wireless communication device can typically be rechargedperiodically (e.g., nightly), wireless peripheral devices are notrecharged as frequently, they typically operate for longer periods oftime off a single charge, and they usually are powered by smallerbatteries than those in the wireless communication device. Therefore, itis desirable for the power consumption of the transceiver on thewireless peripheral device to be significantly smaller than that of thewireless communication device, and it is desirable for the powerconsumption on the wireless peripheral device to be adequately managedso as to provide long battery lifetime.

Wireless peripheral devices typically can either set their transceiversinto a low-power “sleep” mode, or turn them off entirely, to reduce thepower consumption. This is typically referred to as “duty cycling”.Problematic situations, however, can arise when a wireless communicationdevice attempts to wirelessly communicate with the wireless peripheraldevice during such “sleep” and/or “off” modes when the wirelessperipheral device's transceiver is powered off and unable to receivemessages from the wireless communication device. This presents atradeoff between the latency in communicating with a wireless peripheraldevice, and the power consumed by the wireless transceiver on thewireless peripheral device. More frequent turning on of the wirelesstransceiver leads to lower latency, but higher average powerconsumption, and vice versa.

Accordingly, a need exists for apparatus and methods that allow awireless communication device to wirelessly communicate with a wirelessperipheral device while the wireless peripheral device is in a low power“sleep” mode, with its main wireless transceiver in the “sleep” or“standby” mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic illustration of a communication system thatincludes a wireless communication device and a wireless peripheraldevice, according to an embodiment.

FIG. 1B is a schematic illustration of a communication system thatincludes a wireless communication device and a wireless peripheraldevice having an ultra-low power (ULP) wireless transceiver, accordingto an embodiment.

FIG. 2 is a schematic illustration of an asymmetric communication systemthat includes a wireless communication device and a wireless peripheraldevice, according to an embodiment.

FIG. 3 is a state diagram that illustrates a method of communication ofa Bluetooth® compliant wireless transceiver, according to an embodiment.

FIG. 4 shows an example of encoding a message in the transitions betweenstates of a Bluetooth® compliant device supporting mandatory standby andpage modes, according to an embodiment.

FIG. 5 is a system block diagram of an ultra-low power (ULP) wirelesstransceiver, according to an embodiment.

FIG. 6 is a flowchart illustrating a method by which the controlsoftware executed by a wireless communication device can communicatewith an ULP wireless transceiver, according to an embodiment.

FIG. 7 is a flowchart illustrating a method by which an ULP wirelesstransceiver can communicate with a wireless communication device,according to an embodiment.

FIG. 8 is a diagram of a prior art wireless network.

FIG. 9 is a diagram of a wireless network system according to anembodiment.

FIG. 10 is a diagram of a wireless network system according to anembodiment.

FIG. 11 is a diagram illustrating methods of encoding backchannelinformation on a beacon signal.

FIG. 12 is a signal diagram illustrating a method of encodingbackchannel information on a beacon or broadcast signal according to anembodiment.

FIG. 13 is a signal diagram illustrating a method of encodingbackchannel information on a beacon or broadcast signal according to anembodiment.

FIG. 14 is a signal diagram illustrating a method of encodingbackchannel information on a beacon or broadcast signal according to anembodiment.

FIG. 15 is a signal diagram illustrating a method of encodingbackchannel information on a beacon or broadcast signal according to anembodiment.

FIG. 16 is a signal diagram illustrating a method of encodingbackchannel information on a beacon or broadcast signal according to anembodiment.

FIGS. 17A-17E are signal diagrams illustrating a method of encodingbackchannel information on a beacon or broadcast signal according to anembodiment.

FIG. 18 is a flow diagram illustrating a method of communicating with adevice in a wireless network using backchannel communication accordingto an embodiment.

DETAILED DESCRIPTION

Embodiments described enable low power wireless devices that are notcompliant (or only partially compliant) with one or more standardprotocols to communicate with fully compliant wireless devices. Invarious embodiments, a compliant signal is modulated for transmission tothe low power wireless device such that the low power wireless devicereceives meaningful data without being required to demodulate theprotocol. Described herein are methods and apparatus for using“backchannel” communication over standard wireless communicationprotocols, including wireless protocols that typically senddevice-to-device communications, and also described are backchannelcommunication leveraging beacon (also known as broadcast) protocols thattypically operate in a contained network environment (e.g. a piconet).The term “backchannel” as used herein, infers using networked processorsto maintain a real-time online conversation alongside the primary groupactivity while not disturbing the primary group activity orconversations that take place according to the standard protocol beingused.

Embodiments described include examples of wireless backchannelcommunication in a general sense (as illustrated and described withreference to FIG. 1A-FIG. 7), and then a more specific application tobeacon or broadcast transmissions (for example, in the context ofpiconets (as illustrated and described with reference to FIG. 8-FIG.18).

I. Backchannel Communication Described Generally as Illustrated by anExample in a Wireless Network with a Low Power Peripheral Device

FIGS. 1A-FIG. 7 illustrate embodiments of an apparatus and method forcommunication between a protocol compliant wireless device and anon-protocol compliant low power wireless device. FIG. 1A is a schematicillustration of a communication system that includes a wirelesscommunication device and a wireless peripheral device, according to anembodiment. The system 100 includes a wireless communication device 105in wireless communication with wireless peripheral device 115. Both thewireless communication device 105 and the wireless peripheral device 115include wireless transceivers that comply with one or multiple standardwireless communication protocols. The wireless communication device 105can be any access point, such as, for example a Wi-Fi router or ZigBeebase station; or 105 can be any mobile wireless communication devicesuch as, for example, a laptop computer, a personal digital assistant(PDA), a standard cellular phone, a smart phone, a tablet personalcomputer (PC). The wireless communication device 105 includes a(standard protocol compliant) wireless transceiver 110. The wirelesstransceiver 110 can include one or multiple wireless port(s). Thewireless port(s) in the wireless transceiver 110 can send and/or receivewireless signals such as, for example, wireless radio frequency (RF)signals via a variety of wireless communication protocols such as, forexample, wireless fidelity (Wi-Fi®) protocol, Bluetooth® 4.0 protocol,cellular protocol (e.g., third generation mobile telecommunications (3G)or fourth generation mobile telecommunications (4G) protocol), 4G longterm evolution (4G LTE) protocol), Near Field Communication (NFC)protocol.

The wireless peripheral device 115 can be any wireless peripheral devicesuch as, for example, a headset, a stereo, a computer mouse, anelectronic pen or stylus. The wireless peripheral device 115 includes a(standard protocol compliant) wireless transceiver 120. The wirelesstransceiver 120 can include one or multiple wireless port(s). Thewireless port(s) in the wireless transceiver 120 can send and receivewireless signals via a variety of wireless communication protocols suchas, for example, wireless fidelity (Wi-Fi®) protocol, Bluetooth® 4.0protocol, cellular protocol (e.g., third generation mobiletelecommunications (3G) or fourth generation mobile telecommunications(4G) protocol), 4G long term evolution (4G LTE) protocol), Near FieldCommunication (NFC) protocol.

Although not shown in FIG. 1A, any number of communication networks canbe operatively coupled to the wireless communication device 105 to allowwireless communication device 105 to communicate with other wirelessand/or wired communication devices. For example, such communicationnetworks can be any type of network (e.g., a local area network (LAN), awide area network (WAN), a virtual network, and a telecommunicationsnetwork implemented as a wired network and/or wireless network. Asdescribed in further detail herein, in some embodiments, for example,the wireless communication device 105 can be connected to the wirelessperipheral device 115 and/or any other device via the communicationnetwork that can include an intranet, an Internet Service Provider (ISP)and the Internet, a cellular network.

In the configuration shown in FIG. 1A, the wireless communication device105 can establish a wireless communication session with the wirelessperipheral device 115 via any of the wireless communication standardsdiscussed above. Each of the wireless transceiver 110 and the wirelesstransceiver 120 includes a wireless transmitter circuit that is designedto enable communication via one or more of the specific standardwireless communication protocols such as the standard wirelesscommunication protocols discussed above. Such wireless standardprotocols typically have mandatory modes that are supported for an IC tobe considered “compliant” with that standard. Because of the highcomplexity of such wireless communication standards, significant“overhead” circuitry is typically included in the ICs that are used tosupport the standard-compliant functionality. Hence, such wirelesstransceiver ICs that are wireless standard-compliant typically consume asignificant amount of power even when the wireless communication device105 and/or the wireless peripheral device 115 is in an “inactive” or“sleep” mode. This can be problematic especially for the case ofwireless peripheral devices 115 that are not recharged frequently, andtypically operate for long periods of time by drawing power from smallbatteries.

Wireless peripheral device 115 includes an ultra-low power (ULP)wireless transceiver (e.g., an ultra-low power radio) that is notnecessarily completely compliant with a standard wireless communicationprotocol, and yet is still capable of receiving a subset of specificmessages from the wireless communication device's (compliant) wirelesstransceiver. As a result, this ULP wireless transceiver consumes muchless power than a full standard-compliant wireless transceiver, thusextending the battery and operational lifetime of the wirelessperipheral device.

FIG. 1B is a schematic illustration of a communication system thatincludes a wireless communication device and a wireless peripheraldevice having an ultra-low power (ULP) wireless transceiver, accordingto an embodiment. The system 100′ includes a wireless communicationdevice 105 and a wireless peripheral device 130. The wirelesscommunication device 105 includes a wireless transceiver 110 that isfully compliant with one or more of the standard wireless communicationprotocols. The wireless peripheral device 130 includes an ultra-lowpower (ULP) wireless transceiver 150 that is not fully compliant withone or more of the standard wireless communication protocol(s) discussedabove, yet able to communicate in a backchannel

FIG. 2 is a schematic illustration showing more detail of theconfiguration of FIG. 1B. The communication system 200 includes awireless communication device 205 in wireless communication withwireless peripheral device 230. The wireless communication device 205includes a wireless transceiver 225 that complies with one or multiplestandard wireless communication protocols, and the wireless peripheraldevice 230 includes an ULP wireless transceiver 250 that does not fullycomply with the standard wireless communication protocol(s) used by thewireless communication device 205.

The wireless communication device 205 is similar to the wirelesscommunication device 105 shown in FIG. 1B and can be any mobile wirelesscommunication device such as, for example, a laptop computer, a personaldigital assistant (PDA), a standard cellular telephone, a smart phone, atablet personal computer (PC), and/or so forth. The wirelesscommunication device 205 includes a memory (or data storage device) 210,a processor 215, and a wireless transceiver 225. Wireless transceiver225 includes a wireless transmitter circuit 227 and wireless receivercircuit 228.

In an embodiment, the processor 215 executes a signal generation module217, which facilitates backchannel communication as described herein. Asfurther explained with reference to other embodiments, it is notnecessary for a signal generation module to reside on the wirelesscommunication device, but it is one implementation.

The wireless transceiver 225 can include a wireless transmitter circuit227 and a wireless receiver circuit 228. The wireless transmittercircuit 227 can include one or multiple wireless port(s). The wirelessport(s) in the wireless transmitter circuit 227 can send data units(e.g., data packets, data frames, etc.) via a variety of standardwireless communication protocols such as, for example, a wirelessfidelity (Wi-Fi®) protocol, a Bluetooth® 4.0 protocol, a cellularprotocol (e.g., a third generation mobile telecommunications (3G) or afourth generation mobile telecommunications (4G) protocol), 4G long termevolution (4G LTE) protocol), a Near Field Communication (NFC) protocol,and/or the like. The wireless transmitter circuit 227 can send to theULP wireless receiver circuit 254 a wireless signal containing theencoded first information and having changes of a characteristic thatrepresent a second information mutually exclusive from the firstinformation (encoded by the signal generation module 217).

The wireless receiver circuit 228 can include one or multiple wirelessport(s). The wireless port(s) in the wireless receiver circuit 228 canreceive data units (e.g., data packets, data frames, etc.) via a varietyof standard wireless communication protocols such as, for example, awireless fidelity (Wi-Fit) protocol, a Bluetooth® 4.0 protocol, acellular protocol (e.g., a third generation mobile telecommunications(3G) or a fourth generation mobile telecommunications (4G) protocol), 4Glong term evolution (4G LTE) protocol), a Near Field Communication (NFC)protocol, and/or the like. The wireless receiver circuit 228 can have anet power gain of no more than unity before at least one of adownconversion of the RF wireless signal or detection of the RF wirelesssignal.

The wireless peripheral device 230 can be any wireless peripheral devicesuch as, for example, a headset, a stereo, a computer mouse, anelectronic pen or stylus, and/or the like. The wireless peripheraldevice 230 includes a memory (or data storage device) 235, a processor240, and an ultra-low power (ULP) wireless transceiver 250.

The processor 240 includes a signal analysis module 245. The signalanalysis module 245 can be a hardware module and/or software module(that is stored in memory 235 and/or executed in processor 240) and isoperably coupled to the ULP wireless transceiver 250. The signalanalysis module demodulates the backchannel information that istransmitted on the compliant signal.

The ULP wireless transceiver 250 includes a ULP wireless receivercircuit 254 with one or more wireless ports.

A fully standard wireless communication protocol-compliant wirelesstransceiver is typically used to generate, transmit, receive, anddemodulate data units (e.g., data packets, data frames, etc.) thatcomply with a specific standard wireless communication protocol. Dataunits are the primary vehicle for wirelessly transmitting user data ormessages from one communication device to another. For example, theaudio data exchanged between a cellular phone and a wireless headset iscarried in the payloads of multiple data units. The primary goal ofthese transceivers is to transfer the data contained in the payload (thefirst information) from the transmitting device to the receiving device.The methods and apparatus of described herein of encoding informationthrough a characteristic of the standard-compliant packet. For example,one characteristic of the standard-compliant packet is its length. Thelength varies as a function of the amount of data in the payload of thepacket. Therefore, controlling the variation of this length can be usedto encode information. The wireless transceiver can vary the amount ofdata put in the packet based on the second information to be encoded.Therefore, the second information is encoded in the length of thepacket, and decoded by an ULP receiver circuit that measures the lengthof the packet, and need not necessarily decode the first informationcontained in the packet payload. The power consumption of a receivercircuit to measure the packet length (without decoding the firstinformation) can be much lower power than a fully standard-complianttransceiver.

Known wireless transceivers support several modes of operation, referredto as “states” or “modes.” The wireless communication device (e.g., acellular phone, a smart phone, a personal digital assistant (PDA), atablet personal computer (PC), etc.) controlling a wireless transceiver(e.g., a radio) can direct the wireless transceiver to enter a certainstate, or the wireless transceiver may transition between statesautomatically according to policies outlined in the standard wirelesscommunication protocol. In any given operating state, the wirelesstransceiver can transmit data units that take on a state-specificstructure, or the wireless transceiver can modify the rate at which dataunits are transmitted or the channel center frequency on which the dataunits are transmitted or, in some instances, the wireless transceivermay not transmit any data units (e.g., a power-down state). Thefollowing discussion relates to apparatus and methods to include and/ormodulate a digital message via the higher-level operating states of awireless transceiver. The following sub-sections describe examples ofthe modulation formats.

On-Off Keying Modulation by Turning a Radio on/Off

Initially, when the wireless transceiver is not in use, the wirelesstransceiver is in the “standby” mode or a “sleep” mode. The “standby”mode refers to a low power mode for the wireless transceiver thattypically can save significantly on electrical power consumptioncompared to leaving the wireless transceiver in the “active” or “on”mode. Additionally, when the wireless transceiver is turned on from a“standby” mode, the device controlling the wireless transceiver canavoid having to reissue instructions or to wait for a reboot.

Turning on the wireless transceiver immediately puts the wirelesstransceiver into a “scan” mode in which scan data units (e.g., datapackets) are transmitted. Turning the wireless transceiver off ceasesall transmissions. By turning the wireless transceiver on/off with aspecific timing sequence, a message can be encoded into the on/offpattern that is observed by an ULP wireless transceiver that onlydetects the presence/absence of transmitted data units. This techniqueresembles on/off keying (OOK) modulation, except that the individualsymbols are represented by the on/off state of the standard (commercial)the wireless transceiver that is fully compliant with a standardwireless communication protocol. In one example of this technique, thisis analogous to Morse code communication where “dashes” and “dots” areencoded by the length of time a wireless transceiver is left on and inthe scan mode each time the wireless transceiver is turned on. By usingan ULP receiver circuit that can detect the presence of a packet, it candecode the information.

It is also understood that the same effect of modulating the on/offstate of a wireless transmitter can be accomplished a variety ofdifferent ways, not just by strictly changing the “state” of thetransmitter. This can include, for example, changing the settings in thetransceiver circuit (by reprogramming software or changing hardware),changing enable states of external components to the transceiver (suchas an external power amplifier or a transmit/receiver switch), etc.

Packet-Length Modulation

Wireless transceivers typically use variable length data units, wherethe length of the data unit varies and depends on the amount of datathat is included in the payload of the data unit. Hence, information canbe encoded in the length of a data unit. For example, the wirelesscommunication device (e.g., a cellular phone) could generate a sequenceof data units containing dummy data in their payloads that, for example,can alternate between minimal length and maximum length, in a patternthat encodes a specific message. The message can be demodulated by usingan ULP wireless transceiver that can detect the data unit length withoutdemodulating the contents of the data unit. By using an ULP receivercircuit that can detect the presence of a packet and measure its length,or the length of a series of packets, the ULP receiver circuit candecode the information.

It is also understood that the length of transmission can be modulatedin a variety of ways, not just by changing the length of the data unit.A series of packets can also be considered together as one transmissionwith a length represented by the series of packets, and changing thenumber of packets in the series therefore changes this length.

Packet-Position Modulation

Data units (e.g., data packets, data frames, etc.) are typicallytransmitted immediately when there is data to be sent by the wirelesstransceiver, often times according to a timing protocol defined by thewireless standard. Therefore, a device controlling the wirelesstransceiver could trigger the generation of a data unit by sending dummydata to the wireless transceiver. Information could be encoded by, forexample, sending dummy data to the wireless transceiver at very specificinstants in time, generating data units at these instants in time, in apattern that encodes a specific message. The message could bedemodulated by using an ULP wireless transceiver that can detect thepresence of data units and can measure the relative time that the dataunits arrive, without demodulating the contents of the data unit. Byusing an ULP receiver circuit capable of detecting the time at which apacket arrives, the ULP receiver circuit can decode the secondinformation.

It is understood that the wireless transceiver could alter thetransmission times of packets in a number of ways including, forexample, by changing the scheduling of packets in a time divisionmultiple access framework, or by altering the delay of a transmissionthrough software or hardware (where the hardware could be external tothe wireless transceiver).

Packet-Rate Modulation

In some modes of operation, a wireless transceiver can periodicallytransmit broadcast data units requesting other wireless peripheraldevices respond with their current status. The rate of this broadcast isa parameter that can be configured. Information could be encoded in therate at which these broadcast data units are transmitted. For example, awireless communication device (e.g., a cellular phone) could, forexample, alternate between broadcasting at the minimum rate and maximumrate, in a pattern that encodes a specific message. The message could bedemodulated by using an ULP wireless transceiver that can detect therate at which data units are transmitted, without demodulating thecontent of the data units. By using a ULP receiver circuit that candetect the presence of a packet and measure the rate at which packetsare received, the ULP receiver circuit can decode the information.

It is also understood that the packet rate can be changed in a varietyof ways, not specifically for devices that have a broadcast mode.

Channel-Modulation

Wireless transceivers typically operate on one of several channels, ormay include frequency-hopping in which the wireless transceiver channelis changed frequently to spread the communication over a wide range offrequencies (i.e., improving diversity and reliability ofcommunication). Information can be encoded by, for example, directingthe wireless transceiver to switch between specific channels, or switchbetween different hopping sequences, in a pattern that encodes aspecific message. The message could be demodulated by using an ULPwireless transceiver that can detect the channel at which a data unitwas transmitted on, without demodulating the contents of the data unit.By using an ULP receiver circuit that can detect the presence of packetsand the channel they are transmitted on, the ULP receiver circuit candecode the information.

Amplitude Modulation (AM)

A wireless transceiver typically has the ability to control the outputpower of the power amplifier (PA). The transceiver can encodeinformation into the output power level used by the PA. This can beaccomplished, for example, in software (executing on a processor) bychanging settings of the transceiver or external power amplifier.Alternatively, this can be accomplished in hardware by changing orhaving a different circuit, attenuation level, or external switchsettings. An ULP receiving circuit could measure the received powerlevels of a series of packets, and by differentiating between the twolevels decode the secondary information.

Modulate Contents of the Packet

A wireless transceiver typically has the ability to control theinformation that is used in the different sections of a packet it istransmitting. For example, it can control the destination address, thedata in the payload, etc. Normally this data is assumed to be random,and in many cases a scrambler is used in the wireless transceiver asspecified by a standard to ensure the transmitted signal characteristics(e.g. its frequency response) appear random. If the contents of thepacket (e.g. payload data), however, are given a very specific value,the transmitted signal will have a detectable characteristic, such as acertain pattern in the frequency- or time-domain. Different packetcontents therefore produce changes in these characteristics. Therefore,in this embodiment, the wireless transceiver can encode secondaryinformation into very specific packet content to produce a predefinedsequence of changes in the signal characteristics, which may then bedetected and decoded by an ULP wireless receiving circuit.

Specific Example Using Bluetooth® 4.0 Standard

FIG. 3 is a state diagram that illustrates a method of communication 400of a Bluetooth® compliant wireless transceiver, according to anembodiment. The method of communication 400 described in FIG. 3,however, could be more broadly applied to a wireless transceiver that iscompliant with any other standard wireless communication protocolbesides Bluetooth®. According to the Bluetooth® 4.0 standard, everyBluetooth® compliant wireless transceiver is configured to supportseveral mandatory modes and states of operation. The mandatory modes andstates of operation as illustrated in FIG. 3 are described in detail inthe Bluetooth® 4.0 Standard Document entitled “Specification of theBluetooth® System”, version 4.0, volume 0, dated Jun. 30, 2010, thedisclosure of which is incorporated herein by reference in its entirety.

Each mode and state shown in FIG. 3 has a specific function. Forexample, the STANDBY state 402 is the default, low-power state where thewireless transceivers are off (nothing transmitted or received), andonly a timer may be active in the Bluetooth® wireless transceivers. Fromthe STANDBY state 402, the wireless transceiver may only transition intoeither the PAGE states (e.g., page state 404, page scan state 406) orthe INQUIRY states (e.g., inquiry scan state 408, inquiry state 410). Inthe PAGE or INQUIRY states, the master Bluetooth® wireless transceiver(e.g., the wireless transceiver 225 shown in FIG. 2) enters a scanningmode during which the master Bluetooth® wireless transceiver can searchfor new wireless devices with which to pair (INQUIRY), or solicitinformation about previously paired devices (PAGE). The process ofPAGING and INQUIRY for a new wireless device can involve one or multipletransitional states such as, for example, a master response state 412, aslave response state 414 where a slave is defined as a new (fullycompliant or partially compliant) Bluetooth® device (e.g., the ULPwireless transceiver 250 shown in FIG. 2) different from the masterBluetooth® wireless transceiver, an inquiry response state 416. If as aresult of the PAGE or INQUIRY states of the master Bluetooth® wirelesstransceiver, any new wireless device is discovered, the masterBluetooth® wireless transceiver synchronizes to the slave Bluetooth®device so communication can be established between the master Bluetooth®wireless transceiver and the slave Bluetooth® wireless transceiver,after which the two wireless transceivers (both master and slave) cantransition to the CONNECTION state 420. In the CONNECTION state 420,data units are exchanged such as streaming digital voice to/from aheadset or data files to a Bluetooth® peripheral device (e.g., wirelessperipheral device 230 as seen in FIG. 2). This can be referred to asnormal Bluetooth® operation, where data is exchanged in data units(e.g., data packets, data frames, etc.) in each of the states accordingto the Bluetooth® standard. If the CONNECTION state 420 successfullytransmits data units wirelessly between the master Bluetooth® wirelesstransceiver and the slave Bluetooth® wireless transceiver for apre-specified time period, a persistent wireless link (or connection)will be established between the master Bluetooth® wireless transceiverand the slave Bluetooth® wireless transceiver, and the master Bluetooth®wireless transceiver enters into a PARK state 422.

In some configurations described herein, wireless communication betweena master Bluetooth® wireless transceiver and slave Bluetooth® wirelesstransceiver can be achieved by encoding user data into a sequence ofstate changes. This is in contrast with encoding user data into thepayload of a data unit, as specified by the Bluetooth® standard.

FIG. 4 shows an example of encoding a message in the transitions betweenstates of a Bluetooth® compliant device supporting mandatory standby andpage modes, according to an embodiment. The Bluetooth® compliant devicecan be, for example, the master Bluetooth® wireless transceiverdiscussed in FIG. 3. Referring to FIGS. 3 and 4, if the masterBluetooth® wireless transceiver is transitioned rapidly between theSTANDBY state 402 and PAGE states (404 and/or 406) at an interval of 20ms, a unique transmitted signal 500 is produced from the masterBluetooth® wireless transceiver. This unique transmitted signal could berecognized by a slave Bluetooth® wireless transceiver (e.g., wirelessperipheral device 230 as seen in FIG. 2) and interpreted as a messagesuch as, for example, “turn on”. Changing the interval time could beused to denote a set of messages or to address different devices. Forexample, 20 ms intervals between state changes could encode the message“turn on device 1” and 30 ms intervals the message “turn on device 2”,etc. A Bluetooth® compliant wireless transceiver (e.g., a Bluetooth®compliant radio) typically does not transition between these states atthe above mentioned intervals under normal operating conditions,therefore these messages would be recognized as unique. Furthermore, themessage encoded into state changes uses states existing in theBluetooth® standard, therefore any Bluetooth®-compliant master devicecould send such messages. In another configuration, data can be encodedby transitioning a wireless transceiver between the “standby” and“active” states.

FIG. 5 is a system block diagram of an ultra-low power (ULP) wirelesstransceiver, according to an embodiment. The ULP wireless transceiver600 first amplifies at the RF amplifier 605, the wireless (RF) inputsignal sent from a wireless transceiver, and then measures the powerlevel of the received wireless (RF) signal at an RF power detector 610(e.g., a peak-detector circuit). The RF power detector 610 outputs anelectric voltage that is proportional to the magnitude of the RF signalthat arrived at the input terminal of the RF power detector 610. Theoutput voltage from the RF power detector 610 is compared to a thresholdvoltage in an analog comparator 615. The threshold voltage can be apredetermined voltage level that is representative of adequatecommunication between the two wireless transceivers discussed above. Insome instances, when the received power is above the threshold value,the comparator 615 outputs a logical “1”. In other instances, when thereceived power is below the threshold value, the comparator 615 outputsa logical “0”. The output of the comparator 615 can be used forcommunication from a wireless communication device (e.g., a cellularphone that includes a Bluetooth®-compliant wireless transceiver) to thewireless peripheral device (that includes a ULP radio transceiver 600)in the following way.

When the wireless communication device configures its wirelesstransceiver in the “standby” state, no wireless data units aretransmitted by the wireless communication device and the comparatoroutput 617 on the ULP wireless transceiver 600 is a “0”. When thewireless communication device configures its wireless transceiver to the“active” mode, the wireless communication device begins transmittingdata units wirelessly according to the standard wireless communicationprotocol. The ULP wireless transceiver 600 detects the presence of thedata units by measuring an increase in the RF power level, and outputs a“I”. This forms the basic method for communication from the wirelesscommunication device to the wireless peripheral device.

A message or data that is transmitted from a wireless communicationdevice can be received at the wireless peripheral device using the ULPwireless transceiver 600 described above. A digital signal processor(DSP) 620 located after and receiving the comparator output 617 of theULP wireless transceiver 600 can perform message decoding capable ofidentifying patterns in the comparator output 617. The wirelesscommunication device begins transmitting a message by, for example,transitioning its wireless transceiver between the “active” and“standby” states at a regular interval. The DSP 620 on the ULP wirelesstransceiver 600 detects alternating “0” and “1” on the comparator output617 and compares this comparator output 617 to a reference clock (notshown) on the ULP radio receiver. The ULP wireless transceiver 600 thensynchronizes its local clock to the incoming bit sequence, producing a“synchronized clock” locally on the ULP wireless transceiver 600 thatcan later be used to demodulate the incoming wireless data units. Aftera predefined number of cycles alternating between “active/standby”states, the wireless communication device begins encoding data to besent to the wireless peripheral device. At the same regular interval,the wireless communication device transitions its wireless transceiverto the “active” state when a “1” is to be transmitted, and to the“standby” state when a “0” is to be transmitted. The DSP 620 on the ULPwireless transceiver 600 then monitors the comparator output 617, andrecords the value of the comparator output 617 at every interval of thesynchronized clock in, for example, a memory (not shown in FIG. 5). Atevery rising edge of the synchronized clock, either a “0” or a “1” willbe sampled by the DSP 620 and recoded in the memory. The recoded messagecan then be decoded and output by the DSP 620 (not shown in FIG. 5). Forexample, in some instances, the message decoding can be based on thepulse width of the “1” sample values from the comparator output 617.Based on this output, further action can be taken by the ULP wirelesstransceiver 600 or the wireless peripheral device if necessary orappropriate.

The wireless communication device can communicate to the ULP wirelesstransceiver 600 on the wireless peripheral device by using a standardwireless communication protocol compliant transceiver without anymodification to the wireless communication device hardware. Therefore,the control of the wireless transceiver (located in the wirelesscommunication device) to encode and transmit a message to the ULPwireless transceiver 600 can be performed entirely in software on thewireless communication device (also referred to herein as “controlsoftware”). This control software can be stored in a memory of thewireless communication device (e.g., memory 210 in FIG. 2) and/orexecuted in a processor of the wireless communication device (e.g.,processor 215 in FIG. 2). The method by which the wireless communicationdevice controls its wireless transceiver through its control software isdependent on the wireless communication device, wireless communicationdevice operating system, and level of control allowed by permissionssettings of the wireless communication device. The control software canbe written or configured specifically to control the state of thewireless transceiver, transitioning it, for example, between “active”and “standby” states at specific times. This is analogous totransitioning the wireless communication device into and out of“airplane mode,” but doing so periodically and at controlled instants intime.

FIG. 6 is a flowchart illustrating a method by which the controlsoftware executed by a wireless communication device can communicatewith an ULP wireless transceiver, according to an embodiment. The method700 includes the control software starting a communication session withthe ULP wireless transceiver, at 702. Between steps 704-712, the controlsoftware transitions the ULP wireless transceiver between on and offmodes, for example, for a fixed number of cycles and at a periodic rate,to provide a synchronization sequence to which the ULP wirelesstransceiver can synchronize its local clock.

After provisioning the synchronization sequence, between steps 714-724,the control software begins modulating the message to be transmittedonto the on/off state of the wireless transceiver (located in a wirelesscommunication device) at the same rate by only turning the wirelesstransceiver on when a “1” data bit is to be transmitted and turning thewireless transceiver off to transmit a “0” data bit. The controlsoftware continues the steps 714-724 until the entire message has beentransmitted. The control software can alternatively modulate the messagedata by varying the transmit power level of the wireless transceiver,rather than its on/off state, which can be controlled via the controlsoftware with no required changes to the wireless communication devicehardware. After the desired message has been transmitted to the ULPwireless transceiver, the control software can end the transmission ofthe message by bringing the wireless communication device to an “off” ora “standby” state, at 726.

FIG. 7 is a flowchart illustrating a method by which a ULP wirelesstransceiver can communicate with a wireless communication device,according to an embodiment. The method 800 includes receiving at, forexample, a wireless peripheral device that includes a wireless receivercircuit of the ULP wireless transceiver, a wireless signal from awireless communication device, at 802. As described above, the wirelesscommunication device can be any mobile wireless communication devicesuch as, for example, a laptop computer, a personal digital assistant(PDA), a standard cellular phone, a smart phone, a tablet personalcomputer (PC), and/or so forth. The wireless communication device isseparate from the wireless receiver circuit of the ULP wirelesstransceiver and encodes a first information according to a protocol inthe wireless signal. The wireless communication device can send thewireless signal according to any standard wireless communicationprotocol such as, for example, wireless fidelity (Wi-Fit) protocol,Bluetooth® 4.0 protocol, cellular protocol (e.g., third generationmobile telecommunications (3G) or fourth generation mobiletelecommunications (4G) protocol), 4G long term evolution (4G LTE)protocol), Near Field Communication (NFC) protocol, and/or the like. Asdescribed above, the wireless peripheral device can be any wirelessdevice such as, for example, a headset, a stereo, a computer mouse, anelectronic pen or stylus, and/or the like. The wireless receiver circuitof the ULP wireless transceiver is not fully compliant with one or moreof the standard wireless communication protocol(s) discussed above.

At 804, a pre-defined sequence of changes of a characteristic within thewireless signal can be detected by, for example, the wireless receivercircuit of the ULP wireless transceiver, to decode a second informationmutually exclusive from the first information without decoding the firstinformation. As described above, the second information can berepresentative of, for example, transitions between operating states ofthe wireless communication device (e.g., a timing sequence) that canindicate a message to the wireless peripheral device (e.g., a “wake-up”message). In such instances, the wireless receiver circuit of the ULPwireless transceiver can decode the received wireless signal to decodethe second information without decoding the first information encoded inthe wireless signal. At 806, the second information is sent by, forexample, the wireless receiver circuit of the ULP wireless transceiverto, for example, the processor of the wireless peripheral device.

II. Backchannel Communication Described with Reference to anImplementation for Beacon or Broadcast Communications, in Particular ina Star Network Topology

Many deployed wireless networks and wireless standards in use todayadopt what is called a “star” network topology, where there is onecentral access point (AP)/hub/router (the “star”) that connects tomultiple nodes. Nodes do not communicate directly with each other, andany node-to-node communication is done by routing through the accesspoint device. In star networks, the AP and node devices are asymmetric,both in their physical design (size, power envelope, components),application (plugged in, wireless), and networking protocols(duty-cycling, broadcasting, relays). For example, a Wi-Fi AP istypically plugged in to a wall, continuously broadcasting its ID(network name), and always listening for new nodes requesting access tothe network. In contrast, Wi-Fi nodes are often battery operated, do notbroadcast their identity, and only communicate with the AP when needed(to send/receive data or maintain association with the network).Bluetooth Low-Energy (BLE) adopts a similar network topology, where oneAP (e.g. a cell phone) broadcasts its identity and continuously monitorsfor BLE devices to connect to. Multiple BLE devices can connect to oneAP. When not in range of the AP, the BLE peripheral devices go into asleep state to save power. The IEEE 802.15.4 (and derivative) standardfollows a similar topology, in this case AP generates beacons that nodedevices can use to synchronize to.

FIG. 8 is a diagram of a prior art star network 900 including an AP 903and three Nodes (1, 2, and 3). In these types of star networks,embodiments provide the ability to put the nodes into a sleep state withtheir standard-compliant and high-power radio disabled, yet stillmaintain the ability for the AP to wirelessly send data to the nodes(for example a wake up message). In the case of networks with an AP thatcontinuously generates a broadcast or beacon, embodiments encodebackchannel information is encoded onto the broadcast message. Thebackchannel information reaches all nodes within broadcast range, andprovides a continuous stream of network messages for sending informationto the lower power node devices over the established backchannel.

FIGS. 9-18 illustrate embodiments of an apparatus and method forbroadcast, multicast and beacon wireless networks, including modulatingbeacon signals to create a backchannel via meaningful signals aretransmitted to an ULP receiver. The ULP receiver may be capable ofreceiving only, and not capable of transmitting. Wireless systems thatoperate from a battery and/or from power harvested from the environmentneed only consume small amounts of energy to prolong the system lifetimefor a given amount of available energy. The energy budget for a wirelesssystem affects a widening set of applications due to a combination ofrequirements for smaller size (less battery volume, so less energyavailable), longer lifetimes (required to make energy last longer),and/or more functionality (requirement to do more with the same amountof energy). An emerging class of these wireless systems can be used in avariety of applications, including providing monitoring, sensing,control, and security functions. An increasing fraction of attention tothese sorts of devices considers that they will need to operate at leastin part using power harvested from their environment, and a new class ofpower harvesting systems on chip (SoCs) has emerged for this purpose.These SoCs may include combinations of power harvesting circuits, powermanagement circuits, sensors or sensor interfaces, processing components(e.g. microcontrollers, microprocessors, digital signal processors,hardware accelerators), memory, and wireless communication circuits(e.g. radios).

FIG. 9 is a diagram of a wireless network system 1000 according to anembodiment that includes an access point, or router 1002. The accesspoint or router 1002 can be any device capable of wireless communicationin the sense understood by those skilled in the art. Therefore, accesspoint or router 1002 includes devices such as mobile phones, tabletcomputers, dedicated router devices in piconets, etc., that include theprocessing hardware, software, and/or firmware to execute the methodsdescribed and claimed herein. The network 900 also includes multiple ULPreceiver nodes 1004A, 1004B, and 1004C. The number of access points andnodes is arbitrary. Receivers 1004 can receive signals from transmittersthat are usually fully compliant (but are not required to be compliant).Receivers 1004 in an embodiment are receive-only devices, but that isnot a requirement. Although most wireless communications rely on somekind of two-way communication (for example hand-shake acknowledgementthat a packet was received), embodiments allow communication withoutacknowledgement on the part of the receiver. In an embodiment, theaccess point 1002 transmits a beacon, which does not typically expect aresponse. The signal generating module 1003 generates a beacontransmission that is regularly broadcast (for example as anadvertising-type of signal). The ULP receivers/nodes 1004 receive thebeacon or broadcast transmission in the normal way. However, the signalgenerating module 1003, in an embodiment, modulates the “normal” beaconsignal in a way that is within the constraints of the beacon orbroadcast protocol used to transmit data in the normal star networkmanner. A signal analysis module 1005 on each of the ULP receivers 1004is capable of demodulating the backchannel element of the normalbroadcast transmission, and therefore communicates without requiring afully compliant (meaning compliant with the broadcast or beacon protocolbeing used in the star network) radio. Examples of embodiments in whichthe methods and systems can be used include Zigbee networks, BLEnetworks, WiFi networks, cellular networks, and other “nonconnectableadvertising” networks.

FIG. 10 is a block diagram of an alternative system 1011 for backchannelcommunication in a beacon or broadcast network. In system 1011, anaccess point or router 1010 is in a star-type network with multiplereceivers/nodes 1004. Access point or router 1010 does not have a signalgenerator such as signal generator 1003 resident on its processors, nordoes the access point or router itself execute a signal generator 1003.Rather, signal generator 1003 executes remotely on servers that areaccessible to the access point or router 1010 via the Internet or anyother network. In this embodiment, a star network can be set up andfunction without instantiation of any signal generationsoftware/hardware/firmware on the access point/router, but yet, thenetwork can benefit from backchannel communications as described hereinto enable the use of low power receivers (nodes) that might not be fullycompliant with the communication standard being employed in the network.This is an example of a situation in which (as an example) a homeownermay have multiple systems in the home controlled by a router in a starnetwork. The router receives wireless signals to control the systems inthe home. These signals may be hosted by or facilitated by a third partyentity that provides a service of (for example) remotely controllinghome systems. In such a situation, the signal generation software 1003can be in the path of this relationship between homeowner andthird-party administrative entity. To reiterate, in this embodiment, theaccess point/router itself (like the nodes) does not necessarily need torun specific software or have specific hardware in order to be anelement of the methods and systems described and claimed herein.

With reference, to FIG. 11, embodiments of a backchannel communicationmethod and system for a beacon/broadcast network include at least threemethods of modulating back-channel information onto the access point(AP) beacon signal: modulating the length of time the AP transmits arepetitive beacon signal, modulating the beacon interval (time betweenbeacon packets), and modulating the length of the beacon packet itself(by modulating how much data is in each beacon packet). AP 1102 (signalgeneration module 1003 is not shown, but is present as shown in eitherof FIG. 9 or 10) is continuously broadcasting information such as itsnetwork name, and other identifying information. Node 1105 (which in anembodiment includes a signal analysis module 1005, not shown) receivesthe broadcast signal from the AP 1102. Typically, the main communicationradio of node 1105 (which is also usually a communication standardcompliant radio) is in a low power mode that implies that itscommunication radio is turned off. However, regardless of whether themain communication radio is turned on for a particular node, the nodecan still be capable of receiving backchannel communications as encodedon the broadcast. This can be referred to as the node having its mainradio off and it ultra-low power (ULP) back-channel receiver on.

FIG. 12 is a diagram illustrating one method of modulating backchannelinformation on standard wireless communications. Using Bluetooth (BT) asan example communication standard, there are various commonly supportedmodes of operation of the BT radio that are programmable through anapplication running on an operating system on the device that hosts theBT radio.

FIG. 12 illustrates a method of performing backchannel communicationbased on a length of time of an AP transmission, or advertising length.When the BT radio is placed in a nonconnectable advertising mode, theamount of data carried in the BT packet can be specified by thetransmitting device, which determines the time duration of the wirelessBT packet (packet length). More data results in a longer-duration BTpacket, and less data results in a shorter-duration packet. Theadvertising pocket interval is typically specified as one of severalpre-defined interval ranges, for example, short, medium, and longintervals. By start and stop advertising from the program or app, theadvertising length can be controlled. All of these mechanisms can becombined as described below to encode information onto a back-channel inthe BLE beacons.

Binary information in wireless systems is encoded onto a set of signals,called symbols. To encode N bits of data, 2^(N) unique symbols arepossible, only one of which is sent at a time depending on what thecurrent N-bits of information are. For back-channel modulationspecifically on beacons, and in the context of back-channelcommunication using BT radios in a cell phone, different symbols can begenerated by specifying different: lengths of beaconing events, packetlengths, or packet intervals.

FIG. 13 is a signal diagram 1300 illustrating the use of two differentpackets lengths to differentiate between symbol “0” and symbol “1”.

Symbol 0 has a beaconing P-length 0. Symbol 1 has a beaconing P-length1, which is different than p length 0.

FIG. 14 is a signal diagram 1400 illustrating the use of two differentpacket intervals (interval 0 and interval 1, respectively) todifferentiate between symbol “0” and symbol “1”.

FIG. 15 is a signal diagram 1500 illustrating the use of two differentadvertising lengths (A-length 0 and A-length 1, respectively) todifferentiate between symbol “0” and symbol “1”.

In an embodiment back-channel information is encoded in the rate atwhich wireless advertising packets are broadcast by the AP transmitter.The information is decoded as illustrated in FIG. 16.

FIG. 16 is a signal diagram 1600 showing the detection of wirelesspackets as signals with power above the noise level, in the presence ofother wireless signals with power above the noise level shown on thereceived signal strength indication (RSSI) axis). The wirelessadvertising packet length and the wireless advertising packet intervalare also indicated. An assumption is that the RF energy is beingmeasured by an ULP receiver, and compared to a baseline energy level.When a wireless advertising packet is being received, the energy levelwill exceed the baseline level, and in an embodiment that is detectedthrough a comparator. When the packet is present, the comparator outputis a 1. When no packet is being received, the energy level falls belowthe baseline causing the comparator output to equal 0.

FIGS. 17A-17E are signal diagrams illustrating a method of combiningpacket length and advertising duration for 2-bits per symbol. Foursymbols are generated. Only one symbol is generated at a time, at afixed symbol rate. The symbol is selected depending on the twoinformation bits to be transmitted.

FIG. 17A is a signal diagram illustrating the generation of symbol [0,0]which is defined as short packet length and short advertising duration.In an embodiment, a short advertising duration is T1.

FIG. 17B is a signal diagram illustrating the generation of symbol [0,1]which is defined as short packet length and long advertising duration.In an embodiment, a long advertising duration is T2.

FIG. 17C is a signal diagram illustrating the generation of symbol [1,0]which is defined as long packet length and short advertising duration.

FIG. 17D is a signal diagram illustrating the generation of symbol [1,1]which is defined as long packet length and long advertising duration.

FIG. 17E illustrates an example backchannel message generated using amethod according to an embodiment.

In an embodiment, the wireless advertising packet identified isperformed by hardware and/or software that operates on the AP, or onbehalf of the AP as follows. The advertising packet length is measuredby looking at length of time the RSSI signal is high.

Filtering is performed for a pre-defined packet length in the wirelessstandard being used (e.g., 100 us-300 us for Bluetooth), and specifiedby the back-channel modulation method as described herein. Packets thatare longer or shorter than the specified length are rejected.

The time between packets (packet interval) is measured by the length oftime the RSSI signal not “high”. In an embodiment this is done by firstfiltering for packets separated by a pre-defined packet interval withinthe wireless standard when a wireless standard compliant radio is in theadvertising mode. The packet interval is defined by the back-channelmodulation method. Packets that arrive before or after that specifiedpacket interval time are rejected. Finally a repetitive sequence ofidentical wireless packets matching the specified packet length andinterval are identified using correlation.

Once the advertising packet has been identified, the advertising length(duration of time the advertising packets are received) is measured. Thestart of the advertising length is identified as the time the firstadvertising packet was received.

The end of the advertising length is identified as the time the lastadvertising packet was received. That is, when the packet length andpacket interval no longer match the pre-defined values, or when no morepackets are received.

The advertising length is measured by the time duration between startand stop, or counting received advertising packets with a known packetinterval.

The advertising length is quantized into a pre-defined set of ranges,specified for back-channel modulation. One combination of packet length,packet interval, and advertising length corresponds to one receivedback-channel symbol (or a “chip”). For example, the advertising lengthfalling in the range of 800 ms to 1200 ms corresponds to Symbol 0, andin the range of 1800 ms to 2200 ms corresponds to Symbol 1, assuming thesame packet length and packet intervals. This can be expanded to M(M=L·N·A) symbols where L is the number of different packet lengths, Nthe number of different packet intervals, and A the number of differentadvertising lengths specified for back-channel modulation.

Once the backchannel message is received by a node, it is decoded asfollows. The sequence of received symbols is correlated with an expectedsequence to detect when back-channel communication is being initiated.Once back-channel communication has been initiated, additional symbolsmay be received as a payload of data carried in the back-channelmessage. This payload is arbitrarily defined, and can be split intodifferent sections such as a header, data frame, and footer. Thispayload could include information such as routing information, sourceand destination addresses, modulation format information, data, errordetection and correction information.

Multiple access mechanisms such as CDMA could be added layered on top ofthis modulation format.

FIG. 18 is a flow diagram of a method 1700 for modulating wirelessnetwork beacons according to an embodiment. As an example, the 802.15.4standard is used as an example wireless standard, but embodiments arenot so limited. In the example described, it is not necessary to havespecial software or hardware present on a network coordinator. Forexample, in a home piconet the last link servers execute the describedmethod. In method 1800), a low power node that is in a sleep state iswoken up by essentially creating a new piconet specifically for thepurpose of communicating a wakeup message to the sleeping node. Thetransmitting radio assumes the role of coordinator, even if there isalready an established coordinator within an existing piconet.Establishing its own piconet independent of an existing piconet assuresthat beacon modulation does not interfere with the existing piconet.

At 1802, the network is scanned for coordinators. Coordinators can alsobe referred to as base stations, routers, or hubs. At 1804, a search fora quiet channel within the network is performed. If there is no currentquiet channel, a retry is performed after a predetermined interval(1806). If a quiet channel is found, the channel is selected, and a newpiconet ID is generated, at 1808. The beacon modulation parameters areset (1810) as previously described. Specific beacon parameters are setto produce the proper beacon length, beacon rate, and beacon repetitionfor the secondary communication.

The piconet is started at 1812, and “n” number of beacons are sent overthe “new” piconet with the specific modulated parameters (1814). If all“n” beacons have been sent, as determined at 1818, the process isfinished. The nodes within the quiet channel have now received beaconsthat include the modulated backchannel information. If there areaddition beacons to be sent, the next beacon interval and parameters areselected (1816), and the additional beacon is sent. This continues untilthe entire back-channel message is complete.

It is intended that some of the methods and apparatus described hereincan be performed by software (stored in memory and executed onhardware), hardware, or a combination thereof. For example, the controlsoftware on the cell phone can be performed by such software and/orhardware. Hardware modules may include, for example, a general-purposeprocessor, a field programmable gate array (FPGA), and/or an applicationspecific integrated circuit (ASIC). Software modules (executed onhardware) can be expressed in a variety of software languages (e.g.,computer code), including C, C++, Java™, Ruby, Visual Basic™, and otherobject-oriented, procedural, or other programming language anddevelopment tools. Examples of computer code include, but are notlimited to, micro-code or micro-instructions, machine instructions, suchas produced by a compiler, code used to produce a web service, and filescontaining higher-level instructions that are executed by a computerusing an interpreter. Additional examples of computer code include, butare not limited to, control signals, encrypted code, and compressedcode.

Some embodiments described herein relate to a computer storage productwith a non-transitory computer-readable medium (also can be referred toas a non-transitory processor-readable medium) having instructions orcomputer code thereon for performing various computer-implementedoperations. The computer-readable medium (or processor-readable medium)is non-transitory in the sense that it does not include transitorypropagating signals per se (e.g., a propagating electromagnetic wavecarrying information on a transmission medium such as space or a cable).The media and computer code (also can be referred to as code) may bethose designed and constructed for the specific purpose or purposes.Examples of non-transitory computer-readable media include, but are notlimited to, magnetic storage media such as hard disks, floppy disks, andmagnetic tape; optical storage media such as Compact Disc/Digital VideoDiscs (CD/DVDs), Compact Disc-Read Only Memories (CD-ROMs), andholographic devices; magneto-optical storage media such as opticaldisks; carrier wave signal processing modules; and hardware devices thatare specially configured to store and execute program code, such asApplication-Specific Integrated Circuits (ASICs), Programmable LogicDevices (PLDs), Read-Only Memory (ROM) and Random-Access Memory (RAM)devices.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Where methods and steps described above indicate certainevents occurring in certain order, the ordering of certain steps may bemodified. Additionally, certain steps may be performed concurrently in aparallel process when possible, as well as performed sequentially asdescribed above. Although various embodiments have been described ashaving particular features and/or combinations of components, otherembodiments are possible having any combination or sub-combination ofany features and/or components from any of the embodiments describedherein.

For example, while many of the embodiments described herein arediscussed in the context of a cell phone, other types of mobilecommunication devices having a commercial radio can be used such as, forexample, a smart phone and a tablet with wireless communicationcapabilities. Similarly, while many of the embodiments described hereinare discussed in the context of sending and receiving data packets, anytype of data unit may be applicable including data cells and dataframes, depending upon the applicable communication standard.

What is claimed is:
 1. A wireless communication method comprising:monitoring broadcast transmissions of a central access point in awireless network comprising the central access point and multiple nodes,wherein the multiple nodes and the central access point are not requiredto be mutually compliant with a standard wireless communicationprotocol; modulating the broadcast transmissions to transmit backchannelinformation in a backchannel to one or more of the multiple nodes, theone or more nodes receiving the modulated broadcast information; and theone or more nodes demodulating the backchannel information such that areal-time backchannel information transfer is maintained alongsideprimary standard wireless communication protocol information transfers.2. The method of claim 1, wherein the broadcast transmissions of thecentral access point are beacon transmissions that require no response.3. The method of claim 1, wherein the real-time backchannel informationtransfer occurs without acknowledgement on the part of a receiving node.4. The system of claim 1, wherein the wireless network comprises anynetwork chosen from a group comprising: a Zigbee network; a WiFinetwork; IEEE 802.15.4; IEEE 802.15.4 4G, 6LowPAN; any cellularstandard, including LTE, and GSM; Bluetooth; and a nonconnectableadvertising network.
 5. The method of claim 1, further comprising:maintaining a main standard wireless communication protocol compliantcommunication radio in an “off” state; and maintaining an ultra-lowpower backchannel receiver in an “on” state to receive backchannelinformation.
 6. The method of claim 1, wherein the modulation of thebroadcast transmission is performed by a signal generating module at thecentral access point.
 7. The method of claim 1, wherein the modulationof the broadcast transmission is performed by a signal generating moduleat servers remote from the network.
 8. The method of claim 1, whereinmodulating the broadcast transmission comprises modulating anadvertising packet length of a beacon transmission.
 9. The method ofclaim 1, wherein modulating the broadcast transmission comprisesmodulating an advertising packet interval.
 10. The method of claim 1,wherein modulating the broadcast transmission comprises modulating anadvertising length of a beacon transmission.
 11. The method of claim 1,wherein modulating the broadcast transmission comprises modulating arate at which advertising packets are broadcast by the central accesspoint.
 12. The method of claim 1, further comprising the one or morenodes detecting broadcast transmissions as signals with power above anoise level in the presence of other signals with power above the noiselevel.
 13. The method of claim 1, further comprising: modulating thebroadcast transmission by modulating both an advertising packet lengthand an advertising duration; and encoding the advertising packet lengthand the advertising duration to represent two binary bits per symbol.14. A wireless network system comprising: a central access pointconfigurable to transmit broadcast messages according to a standardwireless communication protocol; and a plurality of ultra-low power(ULP) nodes in communication with the central access point within awireless network, and wherein the plurality of ULP nodes areconfigurable to receive transmissions from the central access point thatare in a backchannel distinct from a main standard wirelesscommunication protocol channel; and a signal generating module formodulating backchannel information on the broadcast messages.
 15. Thewireless network of claim 14, wherein one or more of the ULP nodes isnot compliant with the standard wireless communication protocol.
 16. Thewireless network system of claim 14, wherein the central access pointcomprises the signal generating module for modulating backchannelinformation on the broadcast messages.
 17. The wireless network systemof claim 14, further comprising one or more servers external to thewireless network, wherein the one or more servers comprise the signalgenerating module for modulating backchannel information on thebroadcast messages.
 18. The wireless network system of claim 14, furthercomprising one or more signal analysis modules on one or more of the ULPnodes for demodulating the backchannel information.
 19. The wirelessnetwork system of claim 14, wherein the signal generating module encodesbackchannel information by modulating more or more of: an advertisingpacket length; an advertising packet interval; an advertising packetfrequency; and an advertising length of transmission.
 20. Anon-transient computer-readable medium having stored thereoninstructions that when executed in a processor cause the performance ofa wireless network backchannel communication method, the methodcomprising: scanning for coordinators within the wireless network,wherein the wireless network comprises a beacon piconet includingultra-low power (ULP) nodes that are in a sleep mode and unable toreceive beacons from a coordinator in a standard wireless protocol;waking up the one or more of the ULP nodes, comprising, finding a quietchannel; selecting a channel; generating a new piconet ID; starting anew piconet; and transmitting one or more beacons to the one or more ULPnodes via the new piconet.
 21. The non-transient computer-readablemedium of claim 20, wherein the method further comprises setting beaconmodulation parameter with which to modulate backchannel information ontothe standard wireless protocol.